Gas-testing apparatus.



B. JOHNSON.

GAS TESTING APPARATUS. APPLICATION FILED DEC. 5, 1912.

Patentd 0ct.7,1913.

'uurrun sTATEs RgrENT ouFIoE.

GAS TESTING APPARATUS.

Specification of Letters Patent.

Patented Oct. '7, 1913.

' Application filed-December 5, 1912. Serial No. 735,072.

To all-whom it may concern:

Be it known that I, EINEnJOI NSON, a citizen of the United States, residing at hlinneapolis, in the county of Hennepin and State of Minnesota, have invented certain newand useful Improvements in Gas-Testing Apparatus;v and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertuins to make and use the same.

My invention has for its object to provide anv improved apparatus .especially adapted for use in determining the efliciency of a set of gas purifiers, such as are used in the manufacture of coal gas or carbureted water gas for illuminating purposes. The invention involves a novel process of obtaining this result. y

In accomplishing the above result, two

diflierent methods have hitherto been employed, one of which is well known as the F gravimetric cadmium chlorid method, and the other,'also well known, as the Tutwiler method. The former method, while accurate, is very slow, and the latter method,

while rapid, is very inaccurate. My invention combines the accuracy of the gravimetric cadmium chlorid method and the rapidity of the Tutwiler method. i

The improved apparatus by which my improved method is accomplished, is illustrated in the single view of drawing which is a vertical section taken centrally through the complete apparatus.

The apparatus is preferably constructed entirely of glass and it includes the following, elements: The numeral 1. indicates a bulb or main body chamber which is sealed at its lower end and contracted at its top where it is fused to a vertically extended tube 2 terminating in what is known .as a- Gre'iner and Friedrichs stop -cock 3. To the sleeve of this stop-cock are "fused the lower ends o-fvertically extended lourettes 4 and These burettes 4 and 5, at their upper ends, are fitted with stoppers 6 and 7, re-

. spectively. The one side of the bulb 1, quite tube 8 terminates at- 8*, and between this point and the outer leg of the U-shaped sec tion '10, the. bulbs 11 and 12 are interposed in the said tube 8.

To the opposite side of the main bulb 1 is fused a tube 13. The inner end of this tube 13 extends downward within the main bulb 1 nearly to the bottom thereof. In the outer portion of said tube 13 is a stop-cock 14. The intermediate portion of the main bulb 1 1s shown as provided with an outwardly pro ecting flange 15 which adapts the apparatus to be supported in an upright position by a suitable clamp, not shown, or by inserting it into a. hole in a block of wood.

The apparatus may be used as follows: In making a determination from 100 to 150 cc. of a strong solution of cadmium chlorid (1.811 grams per liter) is run into the main bulbol from burette 4. through stop cock 3, stop-cock 9 being open, and stop-cock 14 being closed. The apparatus is then tilted into such a position that 5 or 6 cc. of the solution passes into the bulb 11 which acts solution in'the tube 8 from being carried from the apparatus. 'With the apparatus again in its erect position, burette 5, which is preferably graduated to read in tenths of l 00., is filled with a standard solution of iodin, two solutions of different iodin strengthsbeing used, one containing .312 gram of iodin per liter and the other onetenth as strong. The strong solution is of such a strength that 1 cc. is equivalent to .65 gram of hydro en sulfid per 100 cubic feet. One-tenth o a cubic foot of gas 1s used in the determination, and is used in testing the crude gas while the working solution is used in testing partially purified gas. Stopcock 3 is a three-way stop-cock having two oblique passages, one of which, in one position of said valve, connects the burette 4 to the tube 2, the other of which,

vwhen said stop-cock is given a half rotation,

.to 1.5 cubic-feet per hour will pass through as a seal and indicator, preventing traces of,

. the'apparatus. When a color appears in the a perceptible precipitate has formed in the main bulb 1, the gas supply is cut off. If; a perceptible precipitate has not appeared in the main bulb 1, after one-tenth of a cubic foot has passed, a flow is continued until one does appear. Next, the apparatus is directed from the meter and supply removed from its support, the stopcock is opened, (as shown in the drawing) and then the apparatus is so tilted that the solution in the bulb 11 runs back into the main bulb 1. Wash water is drawn in through the tube 8 by applying suction at the top of the burette 4, while the stop-cock 9 is opened and the stop-cock 14 is closed, and then in the same way, by drawing in much water through the tube 13 while the stopcock 9 is closed'and the stop-cock 14 is opened. The gas above the solution in the main tube 1 is removed by opening the stop-cock 9 and applying suction at the top of burette 4.- Next, the stop-cock 3 is closed and fresh starch solution is run into the burette 4. Then the stop-cock 3 is moved back into position shown in the drawings, and this starch solution is caused to run into the main bulb 1. Next, the stop-cocks?) and 14 are again closed and the air in the main bulb 1 is placed under diminished pressure-by applying suction at the upper end of the burette 4, while the stop-cock is, of course, in the position shown in the drawings. The stop-cock 3 is then again closed and 'the burette 4 is filled with concentrated hyd'ro-chloric acid which is .allowed to pass slowly into the main bulb 1 until the precipitated cadmium sulfid is completely dissolved. A. little excess of hydrochloric acid is then run into the said main bulb l'and stop-cock 3 is then closed. The hydrogen sulfid is thus liberated in the main bulb 1, 'under diminished pressure and out'of contact With air, and the same is titrated with the iodin solution. Burette 5 is read and the iodin solution is introduced intermlttently, by carefully opening and closing the stop-cock 3, the apparatus being shaken after each addition. When the starch-iodo, blue color, persists for one-half minute, the end point in titration has been reached. The pink or violet color which appears in the solution must be distinguished from the starch-iodo blue which is the correct end point. Burette 5 is then again read. The apparatus is then emptied, rinsed with water and a blank test run to determine the amount of iodin solution necessary to produce the permanent starchiodo blue color. In making this test, the same amount of starch solution and the same volume of water as is used in the determination, is again used, and the whole acidified with hydro-chlorid acid.' From the amount of gas and the volume of iodin solution used in the determination and in the blank, the number of grains of'hydrogen sulfid per 100 cubic feet of gas is-calculated. For control work, the volume of gas used need not be reduced to its corresponding volume at standard conditions of temperature and pressure.

The uniformly higher results obtained by the gravimetric method may be due to the absorption of sulfur compounds other than hydrogen sulfid, a much larger volume of gas and cadmium chlorid solution being used in the gravimetric method than" in the volumetric method.

The principal advantage of Tutwilers method is its rapidity. A test can be made are less inaccurate, the error amounting to about fifteen per cent." This is,of course, due to the/much greater ratio between the amount of hydrogen sulfid present and the othercompounds with which the io'din reacts. McMillcr states in the original publication of Tutwilers method that fifteen, grains of hydrogen sulfid per cubic feet of gas could escape detection. In the writers experiments, in no case did the Tut- .Wiler show less than ten grains per 100 cubic feet on clean coal gas nor less than four grains per 100- cubic feet. on cleanwa'ter gas. I

The gravimetric cadmium chlorid method is the most accurate in use at the present time. The-great objection to this method, however, in control work, is the length of time required to make a determination. The purifying boxes foul quite rapidly and in determining their efficiency, tests should be made rapidly and as nearly simultaneously at inlet and outlet of purifier, as possible. A method which requires hours for a test becomes impracticable. The large bulk of cadmium chlorid solution used allows absorption of other sulfur compounds than hydrogen sulfid, which, when oxidized with the bromin, give too high results. Another objection is the large amount of cadmium sulfid precipitate required to produce an amount of'barium sulfate which can be several.

readily and accurately weighed. When a sample of 0.1 cubic foot of gas is taken, each milligram of Bast) is equivalent to .116 grain of sulfur per 100 100 cubic feet. Thus, for partially purified gas containing but a fraction of one grain of hydrogen sullid per 100 cubic feet, a number of cubic feet of gas must be used in order to obtain a weighable precipitate.

The volumetric cadmium chlorid method has several advantages over the gravimetric method. Accurate results are obtained on a much smaller volume'of gas; a smaller volume of cadmium chlorid solution causes less absorption of sulfur compounds other than hydrogen sulfid; the method is much more rapid, requiring for a detern'iination instead of hours, from seven to ten minutes, depending upon the purity of the gas.

While in the Tutwiler method, the titration is made under diminished pressure and out of contact with air, it is made in the presence of all of the other constituents of the gas, to-wit, unsaturated hydrocarbon mercopt-a-ns hydrocyanie acid, cyclopentadiene, etc. \Vith my improved apparatus and in accordance with the improved process, the titration is not only made under diminished pressure and out of contact with air, but provides means of making the titration out of contact with the other constituents of the gas. and .which constituents will not affect the iodin solution. This is :1 highly important improvement over the said Tutwiler method.

The advantages of the volumetric cadmium chlorid method over the Tutwiler are Twenty-eight times as-much gas is used in the average determination as is used in the Tutwiler; the burette readings are one-tenth those of the Tutwiler and much more accurate results on gas of low hydrogen sulfid content are obtained. A test can be made in from seven to ten minutes.

What I claim is: 1. A gas testing apparatus comprising a main bulb having an upwardly extended tube and two burettes connected to the upper end thereof, a valve for closing the lower ends of said burettes and for connecting the same, at will, to said tube, a valved tube extending into said main bulb and downward 'within the same, and another valved tube extending from the upper portion of said main bulb. I

2. A gas testing apparatus comprising a main bulb having an upwardly extended tube and two burettes connected to the upper end thereof, a valve for closing the lower ends of said burettes and for connecting the same, at will, to said tube, a valved tube extending into said main bulb and downward .within the same, and another valved tube extending from the upper portion of said main bulb and provided with a U-shaped downward bend adapted to serve as a seal.

main bulb having an upwardly extended tube and two burettes connected to the upper end thereof, a valve for closing the lower ends of said burettes and for connecting the same, at will, to said tube, a valved tube eX- tending into said main bulb and downward within the same, and another valved tube extending from the upper portion of said main bulb and provided with a U-shaped downward depression and a bulb, which bulb is small as compared with said main bulb.

5. The process of determining the amount of hydrogen sulfid in coal gas or other-gas containing the same, which consists, in absorbing the hydrogen sulfid content and allowing the other constituents of the gas to escape, in confining the absorbed hydrogen sulfid gas, and in liberating the said hydrogen sulfid gas, by the use of hydrochloric acid in a partial vacuum, and in titrating under partial vacuum.

In testimony whereof I afiix my signature in presence of two witnesses.

EINER JOHNSON.

l/Vitnesses Em'rI-r E. HANNA, HARRY D. KILGonE. 

